Characterization of the biochemical properties and identification of amino acids forming the catalytic center of 3C-like proteinase of porcine reproductive and respiratory syndrome virus

Abstract

Purpose of work: The non-structural protein 4 (Nsp4) of porcine reproductive and respiratory syndrome virus (PRRSV) functions as a 3C-like proteinase (3CLpro) and plays a pivotal role in gene expression and replication. We have examined the biochemical properties of PRRSV 3CLpro and identified those amino acid residues involved in its catalytic activity as a prelude to developing anti-PRRSV strategies. The 3C-like proteinase (3CLpro) of porcine reproductive and respiratory syndrome virus (PRRSV) was expressed in Escherichia coli and characterized. The optimal temperature and pH for its proteolytic activity were 8°C and 7. 5, respectively. Na+ (1000 mM) and K+ (500 mM) were not inhibitory to its activity but Cu2+, Zn2+, PMSF and EDTA were significantly inhibitory. His39, Asp64 and Ser118 residues were identified to form the catalytic triad of PRRSV 3CLpro by a series of site-directed mutagenesis analysis. © 2010 Springer Science+Business Media B.V.